The invention relates to a primary part for a linear motor, wherein the primary part has at least one laminated core, wherein a first means for production of a first magnetic field is arranged in slots in the laminated core, and a second means for production of a second magnetic field is arranged on teeth of the laminated core, and wherein the primary part is intended for arrangement with a secondary part, and the primary part and the secondary part are separated from one another by an air gap. The invention also relates to a linear motor having a primary part such as this.
Electrical machines have a primary part and a secondary part. By way of example, the secondary part is a rotor of an electrical machine which operates by rotation, or else a moving part of a linear motor. By way of example, the primary part is in the form of a stator or a stationary part, with a single-phase or polyphase winding. In the case of linear motors, both the primary part and the secondary part may be in the form of a moving part.
Stator and rotors for electrical machines generally have a laminated core, comprising individual electrical laminates, wherein the winding or else permanent magnets for generation of magnetic fields is or are arranged on the laminated core. The individual laminates for the stator and rotor are generally stamped individually and are joined together, for example by stamped packaging, welding or brackets to form laminated cores.
In order to guide the main magnetic flux between the stator and the rotor, toothed laminates are normally used for stators/rotors to which windings are fitted. The winding is arranged in the slots in the laminates, or the laminated core. After the slots have been insulated, the winding is introduced, for example by pulling it in.
DE 10 2004 045 992 A1 discloses an electrical machine whose secondary part has no active means, for example windings through which a current can be passed or permanent magnets, for production of a magnetic field. In the case of a synchronous linear motor with permanent excitation and with a secondary part without any permanent magnets, the primary part has windings through which a current can be passed and permanent magnets, wherein the secondary part has only a toothed structure composed of a material containing iron.
Linear motors such as these are used in various fields of technology as drives, in particular direct drives, for example for machine tools, and processing machines such as automatic drilling, milling, turning, placement or bonding machines.
In this case, the linear motors are often subject to adverse environmental conditions. It is impossible to prevent dirt, for example swarf, working liquids such as oils, solid parts, workpieces, etc, from entering the motor area of the primary part, as damaging foreign substances. These foreign substances then also enter in particular the air gap in the linear motor, thus adversely affecting the life of the linear motor. Particularly if the air gap runs horizontally, it is impossible to prevent dirt from accumulating in the air gap or in the primary part or secondary part.